In the field of logging, felled trees and portions thereof are transported over unusually difficult terrain to a landing for further processing. Logging vehicles termed "skidders" are employed to drag loads of logs from the felled location to the destination. Alternative forms of skidders are available, but there are primarily two. One involves skidding with chokers and mainline, and the other involves grapple skidding. Each has definite advantages over the other for a given set of circumstances. The choker-mainline skidder involves connecting logs with a choker and dragging them over the terrain with a mainline. This method allows the operator, under adverse skidding conditions where driving and skidding together are difficult, to drop the drag, move the skidder ahead the full length of the mainline from the drag, then draw or winch the drag up to the skidder location. This is prudent when traversing soft ground, steep adverse grades, or the like. To operate the cable skidding system the operator dismounts the machine, pulls out the mainline chokers, hooks a choker to each tree to be skidded, mounts the skidder and operates the winch to draw the drag of trees to the transport position. At the landing destination, the operator releases the winch which allows the mainline and chokers to fall slack. He dismounts the skidder to unhook each individual choker from the tree stems, which might be all bunched together. The operator then remounts, draws the excess mainline and chokers into the machine and returns for another load.
Grapple skidding generally has distinct advantages over choker skidding particularly in terms of skidding production, operator safety and comfort. Grapple skidders are equipped with a grapple suspended from a boom. The grapple is usually hydraulically operated to open and close. In the open position the grapple is lowered with grapple tines opened to surround the end portions of a load of logs. The grapple is closed and then lifted to a position where the ends of the logs abut the rear end portion of the machine. The operator performs this procedure from the operator station of the machine. In terms of disadvantage, a portion of the weight of the drag is added to that of the vehicle. The vehicle with the drag is limited in its ability to transport the load under adverse terrain conditions. Maneuverability is limited and the added weight increases difficulty in soft terrain or muddy conditions. The grapple skidder must be of sufficient size with adequate horsepower to transport a maximum intended load over the most adverse terrain anticipated and therefore is generally oversized for ordinary skidding conditions.